In prior art, various designs of operating elements for air vents are known. In may cases, these operating elements have a multi-part construction. They may be realized, for instance, in a knob-type design and comprise a separate spring element determining the force required for shifting. Operating elements for air vents, however, are already known in which the spring element is integrated in the operating element.
With such operating elements, the spring element acts on the blade usually in a direct way, whereby the spring element has to withstand a correspondingly high load when a higher shifting force of the operating element is required. With high temperatures, this may result in a creeping behavior of the material whereby the operating forces are correspondingly reduced over the useful life. This has a negative effect on a sensitive adjustment.
Basically, such operating elements are expensive to manufacture in particular if the spring element has to be invisible for the operating person.